Protocol Buffers是Google公司開發的一種數據描述語言，類似于XML能夠將結構化數據序列化，可用于數據存儲、通信協議等方面。現階段支
持C++、JAVA、Python等三種編程語言。
它是一種二進制的格式，比使用 xml 進行數據交換快許多。可以把它用于分布式應用之間的數據通信或者異構環境下的數據交換。
http://code.google.com/intl/zh-CN/apis/protocolbuffers/docs/overview.html （介紹）
http://code.google.com/p/protobuf/downloads/list （下載）
下載安裝
編譯安裝（mingw）：
$ ./configure
$ make
$ make check
$ make install
詳細見：README.txt
如果是Micosoft Visual C++，請參考vsprojects/readme.txt.
在MSYS環境下安裝完后會自動設置好MSYS下的環境變量（PATH）。建議下載代碼的目錄也就是將要安裝好的目錄。
value types can be numbers (integer or floating-point), booleans, strings, raw bytes, or even (as in the example above) other
protocol buffer message types.
specify optional fields, required fields, and repeated fields.
once you've defined your messages, you run the protocol buffer compiler for your application's language on your .proto file to
generate data access classes. These provide simple accessors for each field (like query() and set_query()) as well as methods to
serialize/parse the whole structure to/from raw bytes.
You can add new fields to your message formats without breaking backwards-compatibility; old binaries simply ignore the new field
when parsing. So if you have a communications protocol that uses protocol buffers as its data format, you can extend your protocol
without having to worry about breaking existing code.
Why not just use XML?
Protocol buffers have many advantages over XML for serializing structured data. Protocol buffers:
are simpler
are 3 to 10 times smaller
are 20 to 100 times faster
are less ambiguous
generate data access classes that are easier to use programmatically.
However, protocol buffers are not always a better solution than XML – for instance, protocol buffers would not be a good way to
model a text-based document with markup (e.g. HTML), since you cannot easily interleave structure with text. In addition, XML is
human-readable and human-editable; protocol buffers, at least in their native format, are not. XML is also – to some extent – self-
describing. A protocol buffer is only meaningful if you have the message definition (the .proto file).
To build and install your compiler, follow the instructions in the README.
FAQ:
1 編譯安裝時（make）出現錯誤：
In file included from google/protobuf/compiler/command_line_interface.cc:54:
./google/protobuf/compiler/subprocess.h:80: error: extra qualification
'google::
protobuf::compiler::Subprocess::' on member 'Win32ErrorMessage'
解決：將src/google/protobuf/compiler/subprocess.h:80的
static string Subprocess::Win32ErrorMessage(DWORD error_code); 修改為：
static string Win32ErrorMessage(DWORD error_code);
參考: http://www.fourmilab.ch/fourmilog/archives/2006-05/000699.html
2 編譯時（make）出現錯誤
g++.exe: c:/msys/1.0/mingw/lib/gcc/mingw32/4.4.0/libstdc++.dll.a: No such file or directory
解決：打開mingw下(D:\Qt\2010.05\mingw\lib\gcc\mingw32\4.4.0)的libstdc++.la (C:\Qt\2010.05\mingw\lib\gcc\mingw32\4.4.0下)，將其中的
# Names of this library.
library_names='libstdc++.dll.a'
修改為：
# Names of this library.
library_names='libstdc++.a'
3 編譯時（make）出現彈出框錯誤
"無法啟動此程序，因為計算機中丟失libgcc_s_dw2-1.dll。嘗試重新安裝該程序以解決問題" 或者
the program can't start because libgcc_s_dw2-1.dll is missing from your computer. Try reinstalling the program to fix this problem.
檢查了windows的環境變量和msys里的環境變量（PATH），都已經包含了C:\Qt\2010.05\mingw\bin，且該目錄下有 libgcc_s_dw2-1.dll，但
問題仍然存在
解決：將 libgcc_s_dw2-1.dll（C:\Qt\2010.05\mingw\bin）拷貝到exe的目錄下（protoc.exe所在的目錄C:\TDDOWNLOAD\protobuf-
2.3.0\src）
網上有說到更新libgcc_s_dw2-1.dll 的方法，未試。
參考：http://forums.codeblocks.org/index.php?topic=11313.0
4 在win7上會存在：執行make install時出現/bin/sh: /bin/install: Permission denied錯誤。
解決：將環境變量增加：path：D:\protobuf-2.3.0\src。其中存在protoc.exe文件